1. Field of the Art
This invention relates to an apparatus for producing a polyarylenesulfide (hereinafter sometimes referred to as PAS) by dehalogenation/sulfidation reaction of a hydrous alkali metal sulfide with a dihaloaromatic compound in an aprotic polar organic solvent. Particularly, the invention is directed to an apparatus for obtaining a clean PAS containing no insoluble foreign matter such as metal sulfide. Thus, the present invention encompasses a process for producing such a clean PAS.
2. Prior Art
In recent years high information density has been demanded for recording materials such as magnetic tapes and floppy disks. In order to meet such requirements, higher standards of quality of base films for such recording materials have been demanded with respect to thermal stability, surface smoothness, and other properties.
As to thermal stability, films made from conventional PAS resins may satisfy the above mentioned requirement. However, it cannot be said that the conventional PAS products are satisfactory with respect to surface smoothness. The conventional PAS contains much foreign matter or impurity, such as metal salts, which give rise to uneven film surfaces and marked deterioration of surface smoothness.
The conventional PAS has been produced in a stainless steel reactor by reacting a hydrous alkali metal sulfide with a dihaloaromatic compound in an aprotic polar organic solvent. In such a process, an alkali metal halide produced together with the resulting polymer is soluble in a solvent such as water. It is thus possible to recover PAS by a treatment using a solvent (e.g., water) such as phase separation, extraction and washing. However, during production of PAS with the conventional stainless steel reactor, reaction of the sulfide with the reactor materials takes place to produce metal sulfide (e.g., iron sulfide and nickel sulfide) which are insoluble in a solvent. Such insoluble metal sulfides are not removed to any appreciable extent by post-treatment and remain in the resulting polymer. As a result, the conventional PAS inevitably contains foreign matter, especially heavy metal sulfides, whereby it has been very difficult to produce films of high surface smoothness.